Adjustable bulldozer



July l0, 1956 G. w. MoRK ADJUSTABLE BULLDOZER 4 Sheets-Sheet 1 Filed Nov 5, 1951 /LEORGIE W.. Mom,

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@EGRGE w-MORH,

1N VEN TOR.

ATTORNEY.

July l0, 1956 G. w. MORK 2,753,638

ADJUSTABLE BULLDOZER Filed Nov 5, 1951 4 Sneets-$heet 3 Lfir @Eolcf W2 Mom, INVENTOR.

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ATTORNEY.

July l0, 1956 G. w. MoRK ADJUSTABLE BuLLDozER 4 Sheets-Sheet 4 Filed NOV 5, 1951 United States Patent O ADJUSTABLE BULLDOZER George W. Morir, South Milwaukee, Wis., assignor to Bucyrus-Erie Company, South Milwaukee, Wis., a corporation of Delaware Application November 5, 1951, Serial No. 254,908

Claims. (Cl. 37-144) This invention relates to new and useful improvements in tractor-mounted bulldozers, more particularly to an improved means for effecting tilting of the bulldozer blade about a fore-and-aft axis, and to an improved means for mounting the bulldozer blade on its main supporting frame for such tilting.

ln bulldozers of the type to which this invention is more particularly adapted, a U-shaped blade-supporting frame surrounds the front end of a tractor, the ends of the two branches of the U being pivoted to the sides of the tractor. The center of the base of the U is attached to the rear of the blade by means of a pivot joint which permits the blade to be tilted in a generally vertical plane. In the prior art each end of the blade has in the past been connected to the U-frame by means of a horizontal brace extending forwardly from each side of the U and attachable at various elevations to an arcuate guide on the end of the blade, thus eli'ecting tilting of the blade. (See, for example, U. S. Patent No. 2,308,535 issued January 19, 1943, to T. R. Paulsen.)

The principal objects of the present invention are to provide an improved hydraulically operated tilting bulldozer, in which:

(l) Tilting of the blade can be accomplished by using the potential energy of the weight of the blade and its supporting frame.

(2) Tilting of the blade can be accomplished by means of a single hydraulic cylindenpiston assembly so mounted that it has a direct connection to the blade and its supporting frame.

(3) The blade is so mounted on the supporting frame that: (a) fore-andaft tipping moment about the mounting of the blade due to digging reaction is a minimum, (b) blade thrust is transmitted directly to the bladesupporting frame at points widely spaced both horzontally and vertically in a transverse vertical plane, and (c) each end of the digging edge of the blade will move substantially vertically when the blade is tilted.

(4) The blade can be attached to or removed from its supporting frame with minimum effort and a minimum of simple operations.

(5) The blade can be tilted independently of raising and lowering the blade.

(6) The blade, and its tilting mechanism, is simple and inexpensive to manufacture, assemble and disassemble.

In addition to the objects above stated, a number of novel and useful details have been worked out, which will be readily evident as the description progresses.

The invention consists in the novel parts, and in the combination and arrangement thereof, which are defined in the appended claims, and of which one embodiment is exemplified in the accompanying drawings, which are hereinafter particularly described and explained.

Throughout the description, the same reference number is applied to the same member or to similar members.

Referring now to the accompanying drawings, it will be seen that:

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Figure l is a side elevation of the improved bulldozer, with the tractor indicated in outline only.

Figure 2 is a plan view of the bulldozer shown in Figure l.

Figure 3 is a rear view of the blade and tilting mechanism, taken along the line 3 3 of Figures l and 2.

Figure 4 is a rear View of the blade and blade-supporting frame taken along the line 4 4 of Figures l and 2.

Figure 5 is a schematic diagram showing the hydraulic circuit for controlling the raising and lowering and the tilting of the blade.

Referring now to Figures 1 and 2, it is seen that 11 is the main frame of a conventional tractor (shown in broken-line outline only), mounted on traction units 12, which are pivoted on propelling shaft 13. While the bulldozer of this invention can readily be applied to any usual or commercial type of tractor, it is shown herein in connection with a creeping traction type of tractor.

The bulldozer which is attached to the tractor consists of a blade-supporting frame, a blade, and hydraulic equipment for raising and lowering and tilting the blade.

The blade-supporting frame 14 is roughly U-shaped in plan and includes a pair of transversely-.spaced longtudi nally-extending push beams 1S and 16 respectively, each of which terminates at its rear end in a boss 17 encompassing a horizontal transverse pivot pin rigidly secured to the side of the main frame 11 of the tractor. The push beams 15 and 16 extend forwardly from pins 1S more or less horizontally and parallel to each other, preferably within the spaces between the traction units 12 and the main frame 11, until they terminate forwardly of the main frame 11, their forward ends being rigidly secured to a crossbeam 19 which is included in and constitutes the base of the Uframe. Each push beam has an upstanding bracket 2b which has a pivot 21 for connection to a hydraulic cylinder-piston assembly to raise and lower the U-frame about its pivot axis 18-18, as hereinhere described.

The blade 22 is a built-up structure which includes a front moldboard Z3, a longitudinal digging or cutting edge 24 adjacent the bottom of the moldboard, and longitudinal angle irons 25 and 26 adjacent the top and bottom respectively of the back of the moldboard.

The bulldozer blade 22 is disposed transversely of the tractor main frame in advance of the front crossbeam 19 of the U-frame 14. It is mounted on the Uframe to be tilted in a normally vertical plane about the axis of stud pin 27 which is rigidly secured to the center of the rear face of bottom angle iron 26 and extends rearwardly therefrom to t in a hole 2S in the front of crossbeam 19 adjacent the bottom thereof.

The blade 22 is rotatably held on the front face of crossbeam 19 by means of three inwardly facing concave arcuate rail members 29a, 36a, and 31a (Figure 3) which are welded to the back of the blade adjacent its top and ends respectively at equal radial distances from pin 3.7', and which interlock with three corresponding similarly located oppositely facing convex arcuate rail members 29b, Siib, and 31b on` the front face of crossbeam Although these interlocking arcuate rails are shown in the form of overlapping iinger plates, it is obvious that other types of interlocking members would be equally suitable. Likewise the interlocking members need not necessarily be equidistant from the tilting axis so long as the arc of each pair is centered on that axis. The peripheral length of each pair of interlocking rails is approximately the maximum peripheral travel of the blade for tilting in both directions, so that, when the blade is tilted beyond such maximum, the rails on the blade and cross beam no longer register with each other and the blade can be removed from the U-frame. ln other words` the direct connection between the blade and the U-frame functions as a combined bayonet joint and swivel connection.

Along the top of moldboard 23 is a longitudinal generally` vertical guard plate 32which prevents dirt from spilling over the moldboard and also protects the horizontal .tilt cylinder-piston assembly 33 which lies behind the guard plate 32 and is pivotally connected at one end to bracket 34 behind guard plate 32 on the blade, and at the other end to bracket 35 on the top of crossbeam i9 of the U-frame.

It will be seen that this method of mounting the blade on the U-frame and actuating the blade for tilting has a number of distinct advantages:

(l) The blade is tilted by a simple direct connection of the tilting cylinder-piston assembly to the blade and the supporting U-frame, thus eliminating intervening linkages, 'bel1cran`ks, etc., used in the past.

(2) The blade is iirmly supported by the front crossbeam Vof the U-frame at four widely spaced points that cover a substantial areaof the backof the blade and front of the U-frame, so that digging thrust is well distributed and torque about any one point is a minimum.

(3) Three of the four support points at which the blade bears against the U-frame are adjacent the digging edge so that digging reactions are transmitted directly to the U-frame with minimum tipping torque being imposed on the blade and blade connections to the U-frame.

(4,) Location of the tilt axis adjacent the bottom, and the tilt cylinder adjacent the top, of the blade provides an eiiective moment yarm (equal to the height of the blade) for tilting the vblade and permits use of one small cylinder.

Turning now to Figure in particular, we see that the blade is raised and lowered and tilted hydraulically by the following described hydraulic system.

Pressure fluid for the hydraulic system is supplied from a conventional hydraulic unit 41 which is mounted at the front of the tractor engine (Figure l) and is driven by the tractor. This hydraulic unit comprises an hydraulic storage tanke or tanks, an hydraulic pump, a control valve for thecontrol of the flow of fluid to and from the pump, and various incidental conduits, relief valves, and one-way valves. Since this hydraulic unit is well-known in the art and forms no part of the present invention, it is merely shown schematically in the iigures. Suffice to say ythat the hydraulic runit has two fluid ports 42R and 42L which are connected (as hereinafter described) to the raise and lower ends respectively of the cylinder assemblies (hereinafter described) which the hydraulic unit controls. The plunger 43 of the control valve of the hydraulic unit Vhas live positions to control the ow of iluid to and from the pump P in live cases as follows:

l. "Rase positon.--Fluid under pressure is delivered by the pump P through the raise port 42R of the hydraulic unit to the raise end of .the cylinders 44; return fluid from the lower end of the cylinders through the lower port 42L of the hydraulic unit into the pump intake and tank T.

2. Hold position.-Fluid under .pressure is delivered by the pump P to the valve and then back into the pump again without leaving the hydraulic unit. Fluid ports 42R and 42L of the hydraulic unit are blocked olf. Hence the cylinder pistons are locked in position.

3. "Slow lower poston.-Fluid is delivered by the pump to the valve and then back into the pump. .But the fluid ports 42R and 42L `of the hydraulic unit are not entirely blocked off, there being a slow flow of iluid, under pressure of the weight of the blade, from the raise end of the cylinders, to the raise port 42R of the hydraulic unit, and thence through a bleeder in the control valve of the hydraulic unit to the tank and pump intake.

y4. Lower position-Fluid under pressure is delivered by the pump through Ithe lower port 42L of the hydraulic unit to the lower end of the cylinders; return fluid passing fromthe raise end of the cylinders through the raise port 42K of the hydraulic unit into the pump intake.

5. Float position-Raise and lower ports 42R and 42L of the hydraulic unit and hence the raise and lower ends of the cylinders intercommunicate and communicate, with flow permitted in either direction through the control valve and tank of the hydraulic unit. Hence the piston is free to float in its cylinder.

The hydraulic circuit leading from the raise and lower ports 42K and 42L respectively of hydraulic unit 4l to the raise and lower ends of the lift cylinders 44 and tilt cylinder 33, Will now be described.

Ports 42R and 42L are connected respectively to ports 45R and 45L of lift cylinder assemblies 44 through conduits 46R and 46L respectively. Cylinder assemblies 44 are pivotally connected at 61 to bracket 62 on the tractor main frame and to the push beams 15 and 16 of the U-frame at pivots 21 (see Figures l and 2).

Ports 42R and 42L and conduits 46R and 46L are also connected respectively to input ports 48 and 49 of threeposition spring-centered reversing valve 50 which controls the tilt cylinder assembly 33 and is shown schematically since it is of conventional design. Output ports 51 and 52 of valve 50 are connected respectively to ports 53 (expansion) and 54 (retraction) of tilt cylinder 33 by conduits 55 Vand 56 respectively.

Valve 50 has three positions in which:

(l) Ports 48 and 49 are connected respectively to p orts 51 and 52 connected to ports 53 and 54 of cylinder 33 (clockwise tilting position).

(2) Ports 48, 49, 51 and 52 are blocked (valve in neutral position).

(3) Ports 48 and 49 are connected respectively to ports 52 and 51 connected ,to ports 54 and 53 of cylinder 33 (anticlockwise tilting position).

With the above-described hydraulic circuit there are three methods of power-tilting the blade:

l. `Gravity method-This is the normal method of tilting the blade. With the blade lin raised position, plunger 43 of the control valve of hydraulic unit 41 is set in hold position so that fluid ports 42K and 42L are blocked oif and the weight of the blade will tend to expand cylinder assemblies 44 thereby setting up fluid pressure kin conduits 46R and 47R leading to port 48 of selector valve Si?. Then, if valve 50 is in clockwise tilting position (viewed from the operators seat), pressure iluid will flow from conduit 47R through valve 50, port 51, and conduit 55 to port 53 of cylinder 33, causing it to expand and thereby to tilt Ithe blade clockwise. Return iluid from cylinder 33 i'lows from port 54 .through conduit 56, valve 50, conduits 47L and 46L to port 45L of lift cylinders 44. Piston-rod vdisplacement iiuid required for cylinder assemblies 44 as they expand is supplied to the circuit from the tank of the hydraulic unit through one-way checkvalves 57 and 67 which are Vconnected to conduit 47L. They may be tilted in the opposite anticlockwise direction by merely reversing valve 50 so that pressure fluid flows from conduit A47R through ports 48 and 52 of valve 50 to port 54 of cylinder 33 causing lthe same to retract. Return flow will then kbe from port 53 through conduit 55, ports 51 and 49 to conduit 47L as before. Thus it will be seen that bythe gravity method the blade is tilted by making use of the potential energy of the blade in its raised position to provide pressure iiuid with `which to tilt the blade in either direction. This has the advantage that a slow 4tiltis obtained that permits adjustment of the blade to the exact angle of tilt desired. Such fine adjustmentof tilt angle would be difficult if the blade `were tilted vby using the relatively high-pressure fast-flowing lluid vfromthe hydraulic unit.

2. Power tilt method.-This method is used when a faster positive tilt using pressure fluid from the hydraulic unit 'is desired, and the blade is not llocked in position by rust :or other obstacle. To tilt the blade clockwise .the operator simply throws the selector valve 50 into clockwise tilting position (above described) and the main control valve 43 of the hydraulic unit into raise position, so that pressure fluid from the hydraulic unit and cylinders 44- will flow from conduits 46R and 47R through the selector valve 50 to the port S3 of tilting cylinder 33 as above described. Since the force required to tilt the blade is much less than the force required to lift the entire blade and its supporting frame, the blade will tilt before it starts to rise. This method is often useful to tilt the blade during digging, because the digging reaction will set up a downward component that will prevent the cylinder lil from lifting the blade, so that only the tilting cylinder 33 will operate.

3. Power-lift method.--This method is used where a greater force than is provided by the gravity method is required to tilt the blade when the blade is locked in position by rust or dirt in the blade-mount connections. The operator first hooks the end of the blade that he desires to lower under a tree stump or other object that will hold the blade down, moves the hydraulic unit control valve plunger d3 into raise position, aud the reversing valve 50 into the appropriate clockwise or anticlockwise tilting position. Pressure fluid will then flow not only into the lift cylinders 4M, to retract them and lift the center of the blade with respect to its anchored end and thereby tilt the blade, but also through reversing valve 50 to the tilt cylinder 33 which will also apply a force tending to tilt the cylinder in the same direction. Thus not only are three cylinders acting to tilt the blade, but all of them are actuated by pressure fluid supplied under power from the hydraulic unit instead of by fluid under pressure from the mere weight of the blade. To prevent breakdown from excessive uid pressure if the blade should continue to stick, spring set relief valve 59 is provided. It will be noted that, even though the fluid is at relatively high pressure when this method is used, accurate adjustment of tilt is possible because the fluid is flowing to the large lift cylinders as well as the tilt cylinder and hence speed of tilt is relatively slow.

4. Power-lower method- This method is similar to the power lift method except that the end of the blade that is to be raised is lowered to the ground against a rock or mound leaving the remainder of the blade in the air, and the main control valve is set in lower position and the reversing valve is set in the desired tilt position, so that pressure fluid flows to all three cylinders which all tend to tilt the blade in the desired direction. This method in effect employs the weight of the tractor to tilt the blade.

Having now described and illustrated one form of the invention, it is to be understood that the invention is not to be limited to the specific herein described and shown.

I claim:

. l. In a bulldozer, for attachment to a tractor, the combmation of: a supporting frame adapted to be connected to and raised and lowered with respect to the tractor; a blade tiltably connected to the frame to pivot about a fore-and-aft axis located centrally of the ends of the blade; and hydraulic mechanism to raise and lower the frame and also to tilt the blade with respect to said frame; said mechanism including a double-acting lift cylinder-piston assembly operatively connected to the frame to power raise and power lower the same, a source of pressure fluid for said lift cylinder-piston assembly, a double-acting tilt cylinder-piston assembly pivotally connected between the blade and the frame, and reversible fluid conduits interconnecting said lift and tilt cylinder-piston assemblies in parallel with each other, so that, when the frame is in raised position, the ilud pressure developed in the lift cylinder by the weight of the frame and the blade will be transmitted to the tilt cylinder to actuate the same to tilt the blade, and, when the end of the blade to be raised is lowered to the ground, fluid pressure developed by said source in the lift cylinder and the tilt cylinder will actuate both of said cylinders to tilt the blade.

form or arrangement of parts 2. In a bulldozer, for attachment to a tractor the combination of: a transverse blade; a frame connected with the blade and adapted to be connected with the tractor, whereby the blade and the frame may be raised and lowered as a unit and the blade may be tilted as a unit about a longitudinal axis of the tractor; a double-acting hydraulic lift cylinder piston assembly operatively connected with the frame and adapted to be carried by the tractor to power raise and power lower the frame and blade; a double-acting hydraulic tiltA cylinder piston assembly pivotally connected between the blade and the frame for tilting the blade with respect to the frame; a source of fluid under pressure; fluid connections between said source and said lift cylinder piston assembly; valve control means associated with said uid connections to provide or block at will communication in a selected direction between said source and said lift cylinder-piston assembly; and reversible fluid connections, independent of said control means, interconnecting said assemblies,I whereby, when the control means blocks communication from said source to the lift cylinder piston assembly, the tilt cylinder-piston assembly will be actuated by fluid under pressure of the weight of the blade passing directly from and displaced by the lift cylinder-piston assembly, and, when the control means provides communication from said `source to said lift cylinder-piston assembly to power lower the blade and the end of the blade to be raised is lowered to the ground, said lift cylinder-piston assembly and said tilt cylinderpiston assembly are actuable simultaneously to tilt the blade.

3. A bulldozer according to claim 2, further characterized by having second control means associated with the second-mentioned fluid connections to transmit uid pressure alternatively to one or the other end of the tilt cylinder piston assembly and thereby reverse at will the direction of tilt.

4. In a bulldozer, for attachment to a tractor, the combination of: a blade-supporting frame adapted to be connected to and raised and lowered with respect to the tractor; a transverse blade; a normally vertical transverse bearing plate rigidly mounted on the forward end of the frame, said bearing plate having a vertical dimension approximately equal to that of the blade; and mechanism tiltably connecting the blade to the frame to tilt the blade about a normally horizontal fore-and-aft axis; said mechanism comprising: a pivotal connection between the frame and the blade along said axis centrally of the ends of the blade and adjacent the bottom edge of the bearing plate and the blade; a cylinder-piston assembly having a direct pivotal connection to the back of the blade adjacent the top thereof and a direct pivotal connection to the frame adjacent the top of the bearing plate; and first and second interlock means between the frame and the blade, each means providing a direct bearing contact between the back of the blade and the bearing plate and constraining the blade from fore-and-aft movement relative to the frame for a predetermined range of tilting positions, the first interlock means being adjacent the top of the bearing plate and the top of the blade, and the second interlock means being adjacent the bottom of the bearing plate and the bottom of the blade at transversely spaced points adjacent the sides of the frame, thereby to transmit blade thrust directly to the supporting frame at points widely spaced both horizontally and vertically.

5. In a bulldozer, for attachment to a tractor, the combination of: a blade-supporting frame; a blade having one member of a combined bayonet joint and swivel connection on the rear face thereof disposed centrally of the ends of the blade, the axis of said swivel being normally horizontal and perpendicular to the back of the blade and adjacent the bottom thereof; attaching means comprising the other member of the bayonet connection rigidly mounted on the forward end of the frame, said attaching means providing direct bearing contact between the back of the blade and the frame at a point adjacent the top 0f :the blade and ,at afpjair of transversely spaced points l2,160,596 adjacent Une sides of :the frame; and :power means :to tilt 2,224,724 ,the blade ,abeutsaid vswim/.e1 axis, ,said newer means being 2,311,553 dispsed adjacent the ,19p of 'the beck .of ihe .blade een- .2,344,584 .trelly 0f I .he ends thereof and having a direct pvetel .con- 5 2,4 12,1574 nectin lo the back Yof 111e blade and a digrectvpivotkal con- 2,585,095 nektfion to said other member of -the bayonet ,connection 2,651,121

:References Cited in the le o f this patent UNITED `STATES PATENTS 10 1,977,817 Bird v Oct. 23, 193.4

8 Le Bleu f 1- May 30, 19.39 Felt ?T. `A F Dec. 10, 194() Le Tllmeau A y.- Feb. 16, 1943 Austin Mar. 21, 1944 French V 2 Dec. 17, 1946 Daniels F Feb. 12, 1952 Shannon Sept. 8, 1953 Pursche Ian. 19, 1954 

